Process of making cellulose esters and the products resulting therefrom



Patented Jan. 8 1935 1 UNITED PATENT OFFICE l PROCESS OFfMAK-ING GELLULOSE ESTERS AND THE PRODUCTS RESULTING THERE- FROM Hans T. clarkegNew York,.a;nd Carl J. Malm,

Rochesten N. Y'., assignors to Eastman Kodak Company, Rochester, N. -Y., a corporation of y New York Ne Drawing... Application March 4,1931, Serial 4 No.520,15.0' v

,This invention relates to ,processes, of making 1 organic esters ,-,of cellulose employing an organic.

acid and an alkoxy substituted fattyacid anhydride. This application is impart a continuation.

of our applications l:79,ll'76, and 179,117, bothof Which were filed March 28, 1927, which;havexma-- tured into .Patents 1,800,860 and 1,880,808 respectively. f v j J One object )of theinventionlgis" touprovide a process whereby celluloseesters .ofxmany different organic acids, eithersimple. or mixed, may be prepared- Our .process allowsthe preparation of many organic .es'ters ofwcellulosewhich.

have beeneitherdifficult or impossible. .to prepare heretofore. I

Another object .of our invention is to provide a process in which cellulosic. material may'ibe directly esterified'by. the. organic acids "themselves.

to use either the anhydride or thechloride ofthe fatty acid. In the present?v process, as in. our above applications, the-:e'sterification may be carried out withouttheiuse of the anhydride or chlogroups.

Another. objectof :our invention is to provide a celluloseeesterifying .process in which, asamain initial ingredient, there-isan anhydrideof an er fied cellulosic bodies such as hydrocellulose and reverted cellulose, but can alsoutili'ze substantially undegraded cellulose such as cotton, .sur'- gical cotton WooL tiSsuepaper from-cotton stock,

and sulfite wood pulp, thereby'producingcellu lose esters of high-quality Also othercellulosic materials such as cellulose 'ethers, incompletely acetylated or nitratedcellul'ose may also be further acylated by our process; regardless 10f whether the cellulose wasfirst fully acylated and. a

then hydrolyzed or was only partially acylated' the initialesterification. A still further object is to provide a process which as "it proceeds, by hydration of the anhydride employed, produces a solvent that helps'tokeep the-esterifying ingredients in solution.

A further object of this invention is to provide a new solvent for cellulose-esters such as we pro- Before our. 'inventio'n it has been neces sary in the processes of preparingcellulose.esters ride of the acid which isto furnish desired acyl duce.- As pointed out, this new solvent may be produced in the reaction mass by the hydration of the anhydride whichiwe use or if desired addi tional amounts of this solvent may be addeddirectl-y to the solution. These new solvents (alkoxy fatty'acids) for cellulose estersjhave'been found to be aseffective for allpractical' purposes or-even more so thanrglacial acetic acid but do not contribute acyl groups-to the ester which is unavoidable in the employment of acetic'acid in thepresence of an impelling anhydride...

' A still further object ofr'this invention'is the provisionof valuable cellulose esters of properties,

which are more advantageous for many purposes than thecelluloseesters now. commonly employed inthe manufacture of plastics. Our esters whichcontain higher fatty acid groups have been found;

to have amuchgreater solubility than the esters which do not contain these'higher groups both as-to-thegsolvents inwhich both types of esters aresoluble and as to the solvents in which the ordinary-organic cellulose esters are insoluble.- For example, our products. are soluble. in chloro-' form,,acetone and methyl acetate but in the .case of thecellulose acetates, a material that issoluble'in chloroform will often be found to beinsoluble in acetone and vice versa.

. We have found that the above obj'ects'maybe attained, in general, byfsubjecting the cellulosic materialtoxthe co-action. ofan organic acid containing a cellulose-esterifying group and an alkoxy. substituted aliphatic acid anhydride which impels the esterification without itself supplying .any cellulose-esterifying groups. By the term .cellulose-esterifying groups, 1 we refer to those groups which are capable of combining with the cellulose under the conditions of our process.

The organic acids which we can employ for furnishing such groups canbe selected from the" group-which consists of the unsubstituted aliphatic monocarb'oxylicacid's including the cyclo--' p'araffinic, the aromatic monocarboxylic acids andthe aralkyl monocarboxylic acids; the anhydrides' that'wehavefound particularly suitable in our process are the alkoxy substituted anhydrides of the fatty acids such as methoxy or ethoxy acetic anhydrides, all as described in our above copending applications.

The alkoxy aliphatic 'anhydride present in. the reaction mass takes up any moisture whichmaybe presentand a certain amount of alkoxy aIi- -Q phatic acid is formed whichacts as asolvent for the ingredients of the bath. However, as is fre-- quently desired, further solvent may be added,

preferably such solventsas glacial acetic acid,

methoxy or ethoxy acetic acid (or their esters with the lower aliphatic alcohols such as methyl, ethyl, propyl and butyl), or ethylene chloride, if

desired to aid the thinness and fluidity of the mass. The alkoxy acetic acids are particularly useful as solvents in this process.

The time of the process is shortened and the results are more advantageous when acatalyst' is employed. Any of thewell-known catalysts which are used in acylation of cellulose may be employed, however, we prefer the milder types lysts such as benzene-sulfonic-acid,or parat'olur. ene-sulfo-chloride may also be employed in our process. Of course, almost any of the usual acylation catalysts known to those skilled in the art may be employed under the proper regulation conditions.

'If desired, the esterification may be carried out in the presence of a non-solvent such as ligroin. In that case a dope is not formed but the cellulose after its acylation remains in fibrous form. This'eliminates the step of precipitating which is necessary in the acylation processes carried out in thepresence of a solvent. However, we have found that the acylation is less uniform in fibrous acylationthan in the dope forming processes according toour preferred methods. Example VII is anillustration of this type of acetylation.

Our process is carried out at temperatures above the 1 melting point of the esterifying bath, "but below temperatures at which thecellulose, or the esters made from it are degraded. Such degradation is indicated by brittleness of sheets prepared. fromthe esters. It should be noted that when the ingredients of our baths are mixed together the mixture usually has a lower melting point than V the melting points of the ingredients, taken alone; It'should be further noted that the alkoxy SIIbSti-e tuted fattyacid anhydrides, especially those derived from the simple fatty acids containing less than 10 carbon atoms have a pronouncedsolvent action upon the acids whichwe employ. For in-- stance, 'metho'xy acetic anhydride has :a good solvent action on such difficultly soluble 'mate rials as stearic acid. Moreover, the methoxy acetic acid formed from the methoxy aceticfanhydride during theesterification is likewise a strong and satisfactory solventof the high fatty acids. "There is, therefore, no danger of prematureprecipitation of the ingredients as thereactionproceeds. While the general range of available temperatures is indicated above, we

find it especially convenient to work between 50" C. and, 80 C.,' according to the particular acids and alkoxy fatty acid anhydrides employed. As

will be seen by the'examples hereinaftergiven,.

rapid esterification may be accomplished in a comparatively short time, without degradation of the product, atatemperature of 60 to 65 C, hen ethoxy acetic anhydride and magnesium papenclean cotton, surgical cotton wool, and even sulfite wood pulp, (preferably bleached)- These -materials, especially the cotton materials,

are undegradedwhen they enter our process and;

yield esters which are likewise substantially unimpaired or undegraded, as evidenced by the flexibility of films prepared from them. But our process is likewise applicable to cellulosic materials which have been chemically affected, such as so-called hydrocellulose, reverted cellulose, such as from theviscouse or cuprammoniumprocesses and also lower cellulose nitrates,acetates,'formates, or ethers still containing esterifiable hyrial No. 179,177 in chemically equivalent amount.

I. A bath'was' prepared by mixing 500 lbs. gla- "cial'acetic acid, 600 lbs. of ethoxy acetic anhy- V Qdride and 1 lb. of magnesium perchlorate trihydrate. There was then incorporated in this mixture' 100 lbs.of cleanicotton The bath 'waskept at 60 65? C. until'the cotton fibers disappeared. The bath was. precipitated: in cold methyl alcohol and the precipitateiwas washed and dried. The resulting product was found to be soluble in chloroform. v v

The following examples illustrate other proportions and, ingredients which may be used in curfiprocess j-i Each example is unless otherwise indicated carried 'out substantially similar to the procedure of Example L'y II. 1200 lbs. 'methoxy acetic anhydride, 400 lbs. methoxyi acetic acid, 740 lbs.icommercial stearic acid .(whichi'sa mixtureofstearic and palmitic acids), 130 lbs. glacial acetic acid, 2 lbs. magnesium perchlorate, 100 lbs. of cellulosic material.

I .III; 500, lbs. ethoxy acetic anhydride, 200 lbs.v acetic anhydride,'700 lbs. stearic acid, 2 lbs. paratoluene-sulfo-chloride; 100 lbs. of cellulose.

IV; 300.lbs, ethoxy acetic anhydride, 300 lbs. ethoxy acetic: acid, 200 lbs. commercial stearic acid, lbs. para-toluene sulfo-chloride, 100 lbs.

ethylene chloride, '200-lbs. commercial stearlc acid, 1 0 lbs.' para-toluen'e-sulfo' chloride, 100- lbs. celluloseacetate (36% acetyl). VII.;300 lbs. 'methoxy acetic anhydride, 200 lbsstearic acid, 1,000 lbs. ligroin, 10 lbs. paratoluene-sulfo-chloride,, 100 lbs.'of cellulose ace tate (40% acetyl) at atemperature about the boiling point of the ligroin (90120 C.).

VIII.700lb s., propoxy acetic anhydride, 200 lbs. acetic anhydride,700 lbs. stearic acid, 2 lbs.

fused zinc chloride, 100 lbs. cellulosic material.

, 300 lbs.fethoxy acetic anhydride, 300 lbs. methyl methoxy acetate,-l lbs. lauricacid, '10 lbs.,benzene sulfonic acid, 100'lbs. cellulose .acetate (37.5%acetyl).

Intheexamples which employ cellulose acetate as the cellulosic material the amount of stearyl introduced into the cellulose molecule may be; regulated by thecontent of acetyl groups intheacetate or,;in other words,.by theesterifiable hydroxylspresenti in the cellulose acetate."

For instance, ifya, :cellulose acetate stearate' of high stearyl content is desired,;the cellulose acetate used has a low;ac,etyl.content or vice versa.

.whiletheforegoing examples give all the de-' scription necessary to carry out the esterification' of, United States application .Serial ;No. 179,177; In t a 19$; the. alkoxy acetic. r e, "t e alkoxyanhydrides of homologousz-fatty acidssuch a propion bu r c. e c ma employ as he mpel n ae n d s cds I fi in s m w h mp ;.comme c stearic acid illustrate that, a mixture ofivarious fatty'aoidssnay be employed. in our process 'as is explained in our application No. 179,177. Inthe claims, therefore, where an -,acid is referred to.

it-willgbe understoodto denote either the pure acid orthe-commercialgrade- Also,if desired, various .mixtures of; impelling anhydrides I may,

' be employed in place of the individual-anhydride;

- cial leather, :;of -plastics and other fields in the same- -manner.yin which cellulose esters have hitherto been employed. lt/lanyv of the esters of. the higher :fatty; acids and the aceto higher fatty acidshave qualities which give them exceptional adaptability in this art. vFor example, they give flexible film or ,filamentszwithout softeners or plastifiers; I, but; the acetone-soluble or chloroform-soluble Qplastifiers, heretofore used with cellulose, acetates, may be usedwith them. Triphenyl and .tricresyl phosphates are good examples of the large number which-can be used withintheusualrange of proportions. They can be mixed or laminated-with cellulose nitrate or ace-- tate by meansioftacommon solvent. They can be backedlwith a cellulose acetate layer or with hygroscopic nitrocellulose coatings. to-prevent static, and-these-backingsmay have their electrical conductance improved by containing hy- I groscopic compounds. I 1 5 What we claim ,as our invention .and' desire to secure by Letters Patent of the United: States is: 1. -A process of-makingcellulose esters which. comprises ac'yuung cellulose oracellulose compound-containing Ian esterifiable hydroxyl group with a reaction mixture containing' an alkoxy fatty acid anhydrideand. an acid selected from the groupwhich consists of the unsubstituted aliphatic monocarboxylic acids including thQCY- cloparafiinic, the aromatic monocarboxylic, and the aralkyl-monocarboxylic acids.

2. A process of making cellulose esters which comprises acylating cellulose or a cellulose compound containing an esterifiable hydroxyl group with a reaction mixture containing an ethoxy fatty acid anhydride and an acid selected from the group which consists of the unsubstituted aliphatic monocarboxylic acids including the cycloparaffinic, the aromatic monocarboxylic, and the aralkyl-monocarboxylic acids.

3. A process of making cellulose esters which comprises acylating cellulose or a cellulose compound containing an esterifiable hydroxyl group with a reaction mixture containing an alkoxy fatty acid anhydride, a solvent for the cellulose esters which are produced and an acid selected from the group which consists of the unsubstituted aliphatic monocarboxylic acids including the cycloparafl'inic, the aromatic monocarboxylic,

and the aralkyl-monocarboxylic acids.

4. A process of making cellulose esters which comprises-acylating cellulose; ,or a -cellulose compound containing an esterifiable hydroxyl group With acet anhydrideand'an'acid selected from the group which consists of the unsubstituted'alk phatiomonocarboxylic acids including the cyclo-f paltaffinie the aromatic monocarboxylic .and the reaction materialcontaining an alkoxyaralkyl monocarboxylicacids.

5 .,A,;process of making cellulose esters which comprisesgacylating cellulose or a cellulosecompound containing an esterifiable; hydroxyl group with a reaction mixture-containing ethoxy acetic anhydride andanacidselected from the group vwhich. consists of (the unsubstituted aliphatic monocarboxylic acids including the cycloparaffinic, the-aromatic monocarboxylicand the aralylemonq arb ic ac ds- 7 A- process of making cellulose esters which comprises 'acylating cellulose or a cellulose compound containing an ;.esterifiable hydroxyl group with a reaction. mixture containing ethoxy acetic anhydride and a solvent for the cellulose esters which are-produced and an acid selected from the group which consists of theunsubstituted 311i? phatic monocarboxylic acids including the cyclo,- parafiini thearomatic monocarboxylic and the aralkyl-monocarboxylic acids. v I

1 7.;A process of makingrorganic esters of cellulo se which comprises acylating celluloseacetate with a :reaction mixturecontaining an alko-xy fatty acid anhydride andan acidselected from thegroup which consists of the unsubstituted aliphatic monocarboxylic including the cycloparaiiinic=,-the aromatic monocarboxylic acids and the,arakyl monocarboxylic acids. 8. A -process of. making organic esters of cellulose which comprises treating cellulose acetate with a reaction mixture containing an ethoxy fatty acid anhydride and an acid selected from the group which consists of the unsubstituted aliphatic monocarboxylic acids including the cycloparaffinic, the aromatic monocarboxylic. acids and thearalkyl monocarboxylic acids. 4

, 9. A: process of making organic esters of cellulose; which comprises treating -cellulose acetate with; a reaction mixture containing an alkoxy fatty acid anhydride, a solvent for the cellulose esters produced and an acid-selected from the group which lconsists of the unsubstituted aliphatic monocarboxylicacids including the cycloparafiinic, the aromatic monocarboxylic acids and the aralkyl monocarboxylic acids.

. l0,-;.A processof makingorganic esters-of cellulose. whichcomprisestreating cellulose acetate with. a; reaction mixture containing an alkoxy acetic anhydride and an acid selected from the group which consists of the unsubstituted aliphatic monocarboxylic aralkyl-monocarboxylic acids.

11. A process of making organic esters of cellue lose which comprises treating cellulose acetate with a reaction mixture containing an ethoxy acetic anhydride and an acid selected from the group which consists of the unsubstituted aliphatic monocarboxylic acids including the cycloparafiinic,'the aromatic monocarboxylic acids and thearalkyl monocarboxylic acids.

12. A process of making organic esters of cellulose which comprises treating cellulose acetate with an ethoxy acetic anhydride, a solvent for the cellulose esters produced and an acid selected from the group which consists of the unsubstituted aliphatic monocarboxylic acids including the cycloparafiinic, the aromatic monocarboxylic acids and the aralkyl monocarboxylic acids.

13. A process of making'br'ganic esters of-icellulose which comprises-acylating cellulose ofi fa cellulose compound containing an esteriiiable hydroxyl group with a reaction'mixture containing an-alkoxy-fatty acid anhydride and an acid selected from the groupconsisting of lauric,myris 1 tic, palmitic; stearic; propionic and butyric-acids.

14. A process of making organic esters of cellulose which comprises acylating cellul'ose'j o'r-a cellulose compound containing an esteriflable' hy-' droxyl group with a reaction mixture containing an alkoxy-acetic anhydride and an acid selected from the group consisting of Ilauric, myristic; palmitic, stearic, propionic and butyric acids.

15. A process of making organicesters of cellulosewhich comprise's-acylating cellulose ora cellulose compound containing an esterifiable hydroxyl group with a reaction mixture containing an ethoxy-acetic anhydride and an acid selected from the group consisting of lauric, myristic, palmitic, stearic, propionic and butyric acids.

16; A process of making organic'esters of 'cel-' lulose which comprises acylatingcellulose -or"a cellulose compound containing an'esteriflable hydroxyl group with'a reaction mixture containing an alkoxy-acetic anhydride, a solvent for the cellulose esters produced and an acid selected from the group consisting of lauric, fmyristic, palmitic, stearic, propionic, and butyric acids,

17. A process of making organic esters of :cellulose which comprises treating cellulose or a cellulose compound containing an esterifiable-hydroxyl group with a reaction mixture comprising stearic acid and an alkoxy fatty acid anhydride.

18. A process of makingorganic esters of'cellulose which comprises treating cellulose acetate with a reaction mixture comprising stearic acid and an alkoxy acetic anhydrida' p 19. A process of making organic esters of cellulose which comprises treating cellulose or a cellulose compound containing an esterifiablehydroxyl group with a reaction mixturec'omprising stea-ric acid andan ethoxy fatty acid anhydride.

mixture containing-acetic acid and: an alkoxy fatty acid anhydride. w 7 v 23. A process of making organic esters of cellulose which comprises acylating cellulose or a cellulose compound containing an esterifiableyhydroxyl group with a reaction containing an alkoxy fatty acid anhydride, alkoxy acetic acid and acid selected from the group consisting of thefunsubstitute d aliphatic'monocarboxylic acids including the cycloparaflinic, the aromatic monocarboxylifcandf the aralkyl monocarboxylic acids.""- i A V I 24 A pr'ocess of making organic esters of cellulose "which comprises acylating cellulose or a cellulose compoundcontaining an esteri'flable hydroxyl groupwith areaction mixture containing analkoxy fatty acid anhydride, ethoxy acetic acid and an acidselected f-romthe groupconsisting'o'i an acid selected from the group consisting of the unsubstituted aliphatic monocarboxylic acids in the'unsubstituted aliphatic 'manocarboxylic acids p cluding the cycloparamnic, the aromatic monocarboxylic and the aralkyl monoca'rboxylic acids.

27. The processof acylating cellulose in the presencev of alkoxy acetic acid.

'28; The 1 process of acylatinglcellulosein' the presence of ethoxy aceticacid. I a

29. A process'of making organicies'te'rs of cellulose which comprises reacting upon'a cellulose or a cellulose"compoundcontaining an'esterifiable hydroxyl group with an acylating bath containing an alkoxy' fatty'acid anhydride; 1

30. A process or making organic esters of cellulose which comprises reacting upon a cellulose or a cellulose compound containing an esteriflable hydroxylgroup with an acylating bath containing an alkoxy acetic anhydride. I v 31. VA processof making organic esters of cellulose which'comprises reacting upon a cellulose or a cellulose compound containing" an esterifiable hydroxyl group with an alcylatingbath containing ethoxy acetic anhydride. I I a 1 v HANS -T. CLARKE.

CARL J. 

